Tiger is a lucky kid: She has a monster living under her bed. This monster arrived when Tiger was just a baby. It was supposed to scare her--after all, that's what monsters do. But Tiger was just too cute! Now, Tiger and Monster are best friends. But Monster is a monster, and it needs to scare something. So every night, Monster stands guard and scares all of Tiger's nightmares away. This arrangement works out perfectly, until a nightmare arrives that's too big and scary for even Monster. Only teamwork and a lot of bravery can chase this nightmare away.